The present invention relates to an apparatus and process for conserving enriched oxygen which is subsequently collected under high pressure in a portable container for ambulatory patient use and to permit facile patient mobility. A multi-stage radial compressor is utilized to pressurize the desired gas. The enriched oxygen is fed at a reduced pressure from a product storage tank to a patient, and at the storage tank pressure to generally a buffer tank and subsequently to a radial compressor.
Heretofore, oxygen concentrators have been utilized to supply patients with a gas having a high oxygen concentration for extended periods of time. Oxygen concentrators typically produce a breathable gas containing from about 80 percent to about 96 percent oxygen from atmospheric air and thus have been widely utilized in the home health care field.
U.S. Pat. No. 4,627,860, to Rowland, relates to a microprocessor and cooperating means for monitoring or sensing functions and performance of various components of the concentrator. A test apparatus having means for selecting any of the functions monitored by the microprocessor is connected to the concentrator and displays the selected monitored functions for diagnosing performance levels and component problems or failures.
U.S. Pat. No. 5,071,453, to Hradek et al. relates to an oxygen concentrator which is intended for aircraft use. A booster compressor is used to increase the pressure of the product gas from the concentrator in order to increase the amount of the gas which can be stored in a plenum. The booster includes two moving pistons which are rigidly linked together and a series of check valves which control the flow of gases through the compressor. One of the pistons is driven by air from the rotary valve in the concentrator, and the other piston compresses the product gas for delivery to the plenum. A small sample of concentrator product gas is monitored by an oxygen sensor for oxygen concentration. Once the oxygen concentration has reached an acceptable level, the booster compressor fills the plenum with product gas. Thereafter, if the oxygen concentration of product gas delivered to the crew from the concentrator falls below the concentration which is required at a particular altitude, the product gas stored in the plenum is delivered to the crew. The oxygen sensor monitors the concentrator output product gas to the breathing regulator when the stored plenum gas is not being used.
U.S. Pat. No. 5,354,361, to Coffield, relates to a pressure-swing adsorber system including a pneumatically driven booster compressor to increase the pressure of the output product gas. A pair of inlet valves controls feed air flow to the sieve beds and the drive cylinder of the booster compressor and are cycled so that one valve opens to pressurize one sieve bed before the other valve closes to allow the other sieve bed to vent to atmosphere. During the time that both valves are open, the pressure in the two sieve beds and on opposite sides of the drive cylinder equalize and a portion of the gas in the pressurized sieve bed and drive cylinder side is captured rather than being vented to ambient. System efficiency is increased by selecting whether captured gas from the last pressurized sieve bed or drive cylinder side reaches the next to be pressurized sieve bed first.
U.S. Pat. No. 5,858,062, assigned to Litton Systems, Inc., relates to an apparatus for providing oxygen-enriched air at a first pressure and at a second pressure, the second pressure being greater than the first pressure. The apparatus comprises, in combination, a pressure swing adsorption system and a pressure intensifier. The pressure swing adsorption system for enriching the oxygen content of air has a pressure of at least the first pressure. The pressure swing adsorption system is adapted to provide oxygen-enriched air to a first outlet at the first pressure and to provide oxygen-enriched air to a pressure intensifier at the first pressure. The pressure intensifier pressurizes the oxygen-enriched air and provides the oxygen-enriched air to a second outlet at the second pressure.
It is an aspect of the present invention to provide a method and apparatus for storing high-pressure, high-purity oxygen in a pressure vessel for use in the home health care or related fields as for ambulatory patients, persons confined to wheelchairs, and those who are bedridden.
In accordance with the invention there is provided a method and apparatus for producing from air an oxygen-enriched gas and initially storing the same in a concentrator product tank. At least a portion of the oxygen-enriched gas is fed by different methods as to an optional but desired compressor buffer tank where it is stored. After reaching a predetermined pressure, the gas is fed to a compressor where it is compressed to a high pressure and stored in a mobile or portable high-pressure container. A patient can thus have increased mobility through use of the portable, one or more high-pressure oxygen containers, which can be filled in one""s own home.
It is a further aspect of the invention to provide circuitry to assure prioritization of the flow rate and concentration of the enriched gas to a patient. The excess gas, when available, is simultaneously delivered to an independent, multi-stage compressor.
In accordance with another aspect of the invention there is provided a home health care oxygen concentrator for physically separating molecules of oxygen from air with oxygen in a subsequent operation being fed to a high-pressure vessel. The concentrator comprises one or more molecular sieve beds containing a physical separation material, a first (i.e., feed stock) compressor to provide a feed source of compressed air, control means which regulate the product gas flow through the beds to a concentrator product tank, a second enriched-gas storage tank (e.g., a buffer tank), and a second compressor, e.g., multi-stage, which is not operated by the first compressor but operates independently thereof and enables the oxygen-enriched gas to be compressed and fed to a high-pressure vessel or container.
In a further embodiment, a radial compressor can be utilized to compress oxygen from an optional but desired buffer tank connected to an oxygen source. The radial compressor has pistons radially arranged around a central drive shaft and compresses the oxygen to a high pressure and stores the same in a compact storage cylinder. This design is more compact and less bulky than typical linear designed compressors, and allows the compressor to be housed in a relatively small unit which is thus more easily transportable. An oxygen sensor determines whether a required minimum oxygen concentration is being supplied to a patient and if not, terminates the flow of compressed oxygen to the cylinder, while maintaining the flow to the patient.
Still another embodiment relates to an oxygen storage tank which operatively feeds oxygen-enriched gas to a patient and which also independently and operatively feeds enriched oxygen at a different and generally greater pressure to a buffer tank where subsequently it is compressed by a compressor, independent of an initial compressor for feeding air to the molecular sieves.